Integrated circuit devices such as transistors have increasingly more transistors integrated in dies to meet the increasingly demanding requirement of applications. The saturation currents of the transistors are also increasingly higher in order to achieve faster operation. This results in more heat to be generated in dies. The heat dissipation is thus a severe problem.
Integrated circuit dies typically include a plurality of polymer layers, which are formed over the interconnect structure that is used for interconnecting devices. The polymer layers, however, have low thermal conductivity values. It is very difficult to increase the thermal conductivity of the polymer layers. Although approaches were taken to increase the thermal conductivity of the polymer layers, the manufacturing cost of the high-thermal-conductivity polymer films, however, is very high. This limits the usage of the high-thermal-conductivity polymer films in the integrated circuits.
With the polymer layers being low in efficiency in dissipating heat, the amount of heat that may dissipate through the polymer layers is low. Although the heat may be dissipated through the metal features that are used for conductive electrical signals, overall, the heating dissipating cannot satisfy the requirement of the device die.